Typical turbines are machines that convert fluid motion flowing through the turbine into rotary mechanical motion. Turbines typically have a rotatable center shaft that has rotors or blades or fins attached on the shaft (sometimes referred to as propellers, typically for wind turbines) (hereafter, “blades”). The blades can be encased in a housing or shroud, typically in a reaction turbine.
Fluid flow across the blades imparts a torque action on the blades, thereby causing the shaft to spin, and leaves the fluid flow with diminished kinetic energy exiting the turbine. Typically, these turbines are considered as an impulse turbines, as there is no substantial pressure change of the fluid or gas in the turbine blades. In a reaction turbine, a housing is used to contain and direct the working fluid. Reaction turbines develop torque by reacting to the fluid's pressure or mass. The pressure of the fluid usually changes as it passes through the turbine rotor blades. A housing is not required if the turbine is fully immersed in the fluid flow (such as with river or ocean turbines).
The rotary mechanical motion of a turbine can be converted into electrical power. For instance, if the center shaft is magnetic (or has magnets attached) and the center shaft spins in an armature or windings, then the turbine is structured as part of a generator. The center shaft turbine is not suited to interact with fluids having particulate or other solids within the fluid, as the solids can become trapped between the spinning blades, jamming the turbine and impeding rotary motion.